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Eclipse Platform
Release 3.0

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org.eclipse.ui.progress
Class DeferredTreeContentManager

java.lang.Object
  org.eclipse.ui.progress.DeferredTreeContentManager

public class DeferredTreeContentManager

extends Object

The DeferredContentManager is a class that helps an ITreeContentProvider get its deferred input. NOTE AbstractTreeViewer#isExpandable may need to be implemented in AbstractTreeViewer subclasses with deferred content that use filtering as a call to #getChildren may be required to determine the correct state of the expanding control. AbstractTreeViewers which use this class may wish to sacrifice accuracy of the expandable state indicator for the performance benefits of defering content.

Since:

3.0

See Also:

IDeferredWorkbenchAdapter

Constructor Summary

DeferredTreeContentManager(ITreeContentProvider provider, AbstractTreeViewer viewer)
Create a new instance of the receiver using the supplied content provider and viewer.

DeferredTreeContentManager(ITreeContentProvider provider, AbstractTreeViewer viewer, IWorkbenchPartSite site)
Create a new instance of the receiver using the supplied content provider and viewer.

Method Summary

protected void	addChildren(Object parent, Object[] children, IProgressMonitor monitor) Create a UIJob to add the children to the parent in the tree viewer.
void	cancel(Object parent) Cancel all jobs that are fetching content for the given parent or any of its children.
protected IElementCollector	createElementCollector(Object parent, org.eclipse.ui.internal.progress.PendingUpdateAdapter placeholder) Create the element collector for the receiver.
protected IDeferredWorkbenchAdapter	getAdapter(Object element) Return the IDeferredWorkbenchAdapter for element or the element if it is an instance of IDeferredWorkbenchAdapter.
Object[]	getChildren(Object parent) Returns the child elements of the given element, or in the case of a deferred element, returns a placeholder.
boolean	isDeferredAdapter(Object element) Return whether or not the element is or adapts to an IDeferredWorkbenchAdapter.
boolean	mayHaveChildren(Object element) Provides an optimized lookup for determining if an element has children.
protected void	runClearPlaceholderJob(org.eclipse.ui.internal.progress.PendingUpdateAdapter placeholder) Run a job to clear the placeholder.
protected void	startFetchingDeferredChildren(Object parent, IDeferredWorkbenchAdapter adapter, org.eclipse.ui.internal.progress.PendingUpdateAdapter placeholder) Starts a job and creates a collector for fetching the children of this deferred adapter.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DeferredTreeContentManager

public DeferredTreeContentManager(ITreeContentProvider provider,
                                  AbstractTreeViewer viewer,
                                  IWorkbenchPartSite site)

Create a new instance of the receiver using the supplied content provider and viewer. Run any jobs using the site.

Parameters:

provider -

viewer -

site -

DeferredTreeContentManager

public DeferredTreeContentManager(ITreeContentProvider provider,
                                  AbstractTreeViewer viewer)

Create a new instance of the receiver using the supplied content provider and viewer.

Parameters:

provider - The content provider that will be updated

viewer - The tree viewer that the results are added to

Method Detail

mayHaveChildren

public boolean mayHaveChildren(Object element)

Provides an optimized lookup for determining if an element has children. This is required because elements that are populated lazilly can't answer getChildren just to determine the potential for children. Throw an AssertionFailedException if element is not an instance of IDeferredWorkbenchAdapter.

Parameters:

element - The Object being tested. This should not be null.

Returns:

boolean true if there are potentially children.

Throws:

RuntimeException - if the element is null.

getChildren

public Object[] getChildren(Object parent)

Returns the child elements of the given element, or in the case of a deferred element, returns a placeholder. If a deferred element is used, a job is created to fetch the children in the background.

Parameters:

parent - The parent object.

Returns:

Object[] or null if parent is not an instance of IDeferredWorkbenchAdapter.

getAdapter

protected IDeferredWorkbenchAdapter getAdapter(Object element)

Return the IDeferredWorkbenchAdapter for element or the element if it is an instance of IDeferredWorkbenchAdapter. If it does not exist return null.

Parameters:

element -

Returns:

IDeferredWorkbenchAdapter or null

startFetchingDeferredChildren

protected void startFetchingDeferredChildren(Object parent,
                                             IDeferredWorkbenchAdapter adapter,
                                             org.eclipse.ui.internal.progress.PendingUpdateAdapter placeholder)

Starts a job and creates a collector for fetching the children of this deferred adapter. If children are waiting to be retrieved for this parent already, that job is cancelled and another is started.

Parameters:

parent - The parent object being filled in,

adapter - The adapter being used to fetch the children.

placeholder - The adapter that will be used to indicate that results are pending.

addChildren

protected void addChildren(Object parent,
                           Object[] children,
                           IProgressMonitor monitor)

Create a UIJob to add the children to the parent in the tree viewer.

Parameters:

parent -

children -

monitor -

isDeferredAdapter

public boolean isDeferredAdapter(Object element)

Return whether or not the element is or adapts to an IDeferredWorkbenchAdapter.

Parameters:

element -

Returns:

boolean true if the element is an IDeferredWorkbenchAdapter

runClearPlaceholderJob

protected void runClearPlaceholderJob(org.eclipse.ui.internal.progress.PendingUpdateAdapter placeholder)

Run a job to clear the placeholder. This is used when the update for the tree is complete so that the user is aware that no more updates are pending.

Parameters:

placeholder -

cancel

public void cancel(Object parent)

Cancel all jobs that are fetching content for the given parent or any of its children.

Parameters:

parent -

createElementCollector

protected IElementCollector createElementCollector(Object parent,
                                                   org.eclipse.ui.internal.progress.PendingUpdateAdapter placeholder)

Create the element collector for the receiver.

Parameters:

parent - The parent object being filled in,

placeholder - The adapter that will be used to indicate that results are pending.

Returns:

IElementCollector